Haptic shared control improves tele-operated task performance towards performance in direct control

Abstract

An tele-operation, haptic feedback from the remote environment to the human is often limited, which has been shown to negatively influence the performance and required time of tasks. The conventional research focus is on improving the quality of the haptic feedback (transparency), which may have led to significant improvement, but is still imperfect, with many unresolved issues. The present study presents an alternative approach to improve tele-operated tasks: by offering haptic shared control in which both operator and support system apply the required forces at the input (master) device. It is hypothesized that virtual forces from well-designed shared control will improve required time and accuracy, with less control effort, and that these benefits exist for perfect transparency but even more so for imperfect transparency. In an experimental study haptic shared control was designed to aid operators (n=9) with performing a simple bolt-spanner task using a planar (2D, 3DOF) tele-operator setup. Haptic shared control was compared to normal operation for three types of control: the baseline condition of direct control at the master (perfect transparency), teleoperation with a simple PERR controller, and a PERR controller with feedback gains set to zero (no transparency). The experimental results provided evidence for the hypotheses, showing that all tested tele-manipulation tasks benefit from haptic shared control, for all three levels of transparency. Essentially, the presence of haptic shared control allows for a worse transparency without compromising accuracy or required time, and can even improve accuracy and required time during perfect transparency. Subjective results indicated that the shared control was perceived as helpful and beneficial.